The Melbourne and Queensland number one also looks certain to miss the final at Old Trafford on Saturday week if the Kangaroos get there.
Slater, who missed the final match of the 2012 State of Origin Series and six club games after straining his posterior cruciate ligament (PCL), was helped from the field at Wrexham early in the second half after being hurt in a tackle and went for a scan on Saturday night.
However, his left knee was too swollen to gain a clear diagnosis, according to a n Australian spokesman, who confirmed the player will not play this week and would be doubtful for the final.
Slater's PCL is non-functioning and players can play on without it but he remained in discomfort after the match.
The Kangaroos, who left Manchester on Sunday to set up camp in London, have no shortage of options to cover Slater's absence.
Greg Inglis (South Sydney), Jaryd Hayne (Parramatta) and Darius Boyd (Newcastle) all play full-back for their clubs but play in the threequarter line for their country.
Inglis looks favourite to take over the number one jersey after switching effectively against the Tomahawks.
- Sports & Recreation